Fractures of the distal radius are common. Fractures of the distal radius are often suffered after a fall on the out-stretched hand and are often associated with osteoporosis. Distral radius fractures are frequently accompanied by fractures of the ulnar styloid (with possible injury to the cartilage attached to it) or with injuries to the wrist ligaments. The involvement of the nearby cartilage and ligaments gives rise to the apt description of distal radius fractures as “soft tissue injuries surrounding a broken bone”. The eponym “Colles’ fracture” has been used to describe all distal radius fractures, though that name refers specifically to fractures that are angulated dorsally.
Figure: Colles fracture (http://radiopaedia.org/cases/colles-fracture-1)
Radial height is the distance between two parallel lines perpendicular to the long axis of the radius. The first line is drawn tangential to the distal tip of the radial styloid and the second tangential to the distal ulna. Normal radial height is approximately 12 mm and is decreased in distal radius fractures.
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Figure. Radial height (In this xray, the articular surfaces of the distal ulna and radius lie on the same line, so called "neutral ulnar variance. When ulna projects more distally to the radius, ulnar variance is said to be "positive".)
Radial inclination is the angle between one line drawn perpendicular to the long axis of the radius and a second drawn from the distal tip of the radial styloid to the ulna. Radial inclination ranges from approximately 20 to 25 degrees and is decreased in distal radius fractures.
Figure Radial inclination